System for automatically controlling an electrically propelled traction vehicle traversing a gap in wayside source of power

For use in combination with an electrically propelled land vehicle moving along a predetermined path in a right of way that is paralleled by a sectionalized wayside conductor, adjacent sections of said conductor being respectively energized by different sources of electric power and being electrically insulated from one another at a predetermined transition point along said right of way, said vehicle including a current collector that cooperates with said wayside conductor to provide on board the vehicle a voltage whose magnitude is determined by the voltage magnitude of the power source energizing the particular section of said conductor with which said collector is cooperating, said vehicle additionally including controllable power conditioning means having source and load terminals, means including circuit interrupting means for connecting said source terminals to said current collector, and at least one electric motor connected to the load terminals of said power conditioning means for propelling the vehicle along said right of way in a desired direction as determined by alternative forward and reverse command signals, said power conditioning means including switchable means having alternative states in at least one of which said switchable means is effective to reduce the magnitude of voltage applied to said source terminals, said circuit interrupting means being operable from closed circuit to open circuit positions and vice versa when commanded by trip and reclose signals, respectively, an improved system for automatically controlling said switchable means and said circuit interrupting means in response to the vehicle traversing said predetermined transition point, wherein the improvement comprises:

• a. at least first, second, third, and fourth stationary markers adapted to be placed at predetermined locations in said right of way in the vicinity of said predetermined transition point, the locations of said first and second markers being on one side of said transition point with said first marker being spaced farther than said second marker from said transition point and the locations of said third and fourth markers being on the other side of said transition point with said fourth marker being spaced farther than said third marker from said transition point;
• b. Proximity sensing means placed on said vehicle so as to pass in close proximity to said stationary markers as the vehicle moves along said right of way in the vicinity of said predetermined transition point, said proximity sensing means being arranged to provide, upon passing said first marker and also upon passing said third marker, discrete output signals on a first line and to provide, upon passing said second marker and also upon passing said fourth marker, discrete output signals on a second line;
• c. first means responsive to a forward command signal and to the output signals on said first line for producing a first control signal that starts when said proximity sensing means provides an output signal indicating it is passing said first marker as the vehicle approaches said predetermined transition point from said one side and that terminates when said sensing means provides the next output signal on said first line thereby indicating it is passing said third marker on the other side of said transition point;
• d. second means responsive to a forward command signal and to the output signals on said second line for producing a second control signal that starts when said proximity sensing means provides an output signal indicating it is passing said second marker on said one side of said transition point, said second means also being responsive to said next output signal that is provided on said first line for terminating said second control signal simultaneously with the termination of said first control signal when said third marker is passed;
• e. means responsive to said first control signal for supplying a trip signal to said circuit interrupting means, whereby the circuit between said power conditioning means and said current collector is open as the vehicle traverses said transition point;
• f. means connected to said current collector for measuring the voltage on said collector and, based on that measurement, for indicating the desired state of said switchable means;
• g. means connected to said voltage measuring means and effective only when said circuit interrupting means is open and the actual state of said switchable means does not agree with said desired state for actuating said switchable means to its desired state;
• h. verifying means connected to said voltage measuring means and responsive to the state of said switchable means for producing an agree signal whenever the actual and desired states of said switchable means are in agreement;
• and
• i. means connected to said first and second means and responsive to said agree signal for supplying a reclose signal to said circuit interrupting means when said agree signal is produced and both of said first and second control signals are terminated.